function isEmpty(){
	var searchContent = document.getElementById("searchContent");
	
	var reIsEmpty=/^\s{0,}$/;
	if(reIsEmpty.test(searchContent.value))
	{	
		var searchContentWarning = document.getElementById("searchContentWarning");
		searchContentWarning.innerHTML = "请输入搜索内容";
		return false;
	}
	
	return true;
}

function clearWarning(spanId)
{
	var warningSpan = document.getElementById(spanId);
	warningSpan.innerHTML="";
}